hardhat.config.js

require("@nomiclabs/hardhat-waffle");
require('dotenv').config()
// const fs = require("fs");
// This is a sample Hardhat task. To learn how to create your own go to
// https://hardhat.org/guides/create-task.html
task("accounts", "Prints the list of accounts", async () => {
  const accounts = await ethers.getSigners();

  for (const account of accounts) {
    console.log(account.address);
  }
});

function mnemonic() {
 // return fs.readFileSync("./sk.txt").toString().trim();
 return process.env.PRIVATE_KEY;
 
 
}

// You need to export an object to set up your config
// Go to https://hardhat.org/config/ to learn more
/**
 * @type import('hardhat/config').HardhatUserConfig
 */
module.exports = {
  solidity: {
    compilers: [
      {
        version: '0.8.0',
      },
      {
        version: '0.7.0',
        settings: {},
      },
    ],
  },
  networks: {
    localhost: {
      url: "http://localhost:8545",
      //gasPrice: 125000000000,//you can adjust gasPrice locally to see how much it will cost on production
      /*
        notice no mnemonic here? it will just use account 0 of the hardhat node to deploy
        (you can put in a mnemonic here to set the deployer locally)
      */
    },
    rinkeby: {
      url: "https://rinkeby.infura.io/v3/" + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
      accounts: [
        mnemonic()
      ],
    },
    kovan: {
      url: "https://kovan.infura.io/v3/" + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
      accounts: [
        mnemonic()
      ],
    },
    mainnet: {
      url: "https://mainnet.infura.io/v3/" + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
      accounts: [
        mnemonic()
      ],
    },
    ropsten: {
      url: "https://ropsten.infura.io/v3/" + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
      accounts: [
        mnemonic()
      ],
    },
    matic: {
      url: "https://polygon-mainnet.infura.io/v3/" + process.env.INFURA_ID,
      accounts: [
        mnemonic()
      ]
    },
    matic_mumbai: {
      url: "https://polygon-mumbai.infura.io/v3/" + process.env.INFURA_ID,
      accounts: [
        mnemonic()
      ]
    },
  },
  mocha: {
    timeout: 20000
  }
};